Trial 4

In 1993, the execution-style killing of a Boston police officer sets off a frantic citywide search for suspects.

Police home in on a suspect, a 19-year-old named Sean K. Ellis. Boston journalists and cops recall another murder case that fanned racial tensions.

As Ellis and his lawyers recount his first jury trial, former jurors share their decision processes. A witness's statements are put to the test.

Journalists expose corruption in the Boston Police Department, inspiring Ellis to seek a new trial and perhaps a new lawyer.

Ellis' attorney, Rosemary Scapicchio, remains dogged in her pursuit of the missing documents that may hold the key to her client getting a new trial.

Knowing it's his last chance, Ellis nervously prepares for a fourth murder trial. Also, an investigator searches for an old witness.

As the voters of Suffolk County prepare to elect their next district attorney, Scapicchio digs into who funded the reward for Ellis' conviction.

The election of a new district attorney gives Ellis reason to hope. Later, a hush-hush press conference puts everyone on edge.